Yb(OTf)3-catalyzed propargylation and allenylation of 1,3-dicarbonyl derivatives with propargylic alcohols:: one-pot synthesis of multi-substituted furocoumarin

A highly efficient and mild Lewis acid-catalyzed coupling reaction of 1,3-dicarbonyl compounds with propargylic alcohols has been established. Selective propargylation or allenylation products are obtained depending on the nature of propargylic alcohols. In addition, catalytic quantities of Yb(OTf) 3 can also effectively promote the propargylation and allylation of 4-hydroxycoumarins at the 3-position. By applying this reaction as the key step, a multi-substituted furocoumarin can easily be synthesized in a one-pot procedure. The advantages of this method are broad scope, mild conditions, and easy handling since water is the only side product. (c) 2007 Elsevier Ltd. All rights reserved.